This blog discusses pre-race nutrition for distance runners for improved running performance

In a three part series, Callum looks at the art and science behind race day fuelling. Across the coming series we will look at fuelling strategies for pre-race, mid race and finally post race recovery.

This is part one in that series and focuses on your nutritional strategy in the build up to an  important competition.


The days and hours leading up to a race can be nerve-racking and stressful. There is a lot to think about and get right and the details can send your mind into panic mode. Which socks should I wear? How much should I warm up? What’s the weather going to be like? Will it rain? What if I’ll be running into wind? The list goes on… For an ordinary training session you wouldn’t think twice about these minutiae but If you’ve done several months of hard work all in the hope for a good performance on race day then it’s certainly understandable that you want to get all of the final preparations spot on. One of the biggest questions runners face as race day approaches is that of what to eat. This is a topic which never fails to spark debate in the running community and one I’m sure will continue to be met with mixed opinions for years to come. However, I hope that this article will shed some light on the subject by combining some of my personal experience with some of the established science in the area and thus equip you with the knowledge you need on how to fuel up for your big race.

The days leading up to your race

Recently Gavin wrote a great article about how to stay calm in the build up to a marathon (which you can find here). The emphasis was on the importance of relaxing, staying stress free and keeping your mind away from the race to avoid getting worked up. In my opinion, the same can be said about food. In the week leading up to a race many runners make the mistake of changing their diet drastically in the hope of a better performance only to suffer the consequences when they realise that their bodies aren’t used to this new fuel.

There are lots of diets espoused as ideal for distance running, and indeed some specific foods which have been shown to have endurance enhancing effects. However, if you have not practiced eating these foods during training or less important races, there is a good chance your body won’t like the sudden change and may react negatively. Not what you want on race day!

My advice, like Gavin’s, is that in the week leading up to a big race you should eat meals that you know work for you, the same meals that you eat during your normal everyday training. This way you can relax in the knowledge that you have trained well over the last few months having eaten these foods and that they don’t upset your stomach. Changing your diet at this stage will only place additional stress on top of your already nervous brain and stomach!

With that said, there is substantial evidence to support the theory that ‘carbohydrate loading’ prior to a race can delay the onset of fatigue. ‘Carb loading’ essentially consists of increasing the amount of carbohydrate rich foods in your diet whilst decreasing the amount of protein and fat in the days prior to a race. The basic theory behind this is that increasing the percentage intake of carbohydrates will result in a greater quantity of glycogen being stored in the skeletal muscles. This is the primary fuel used during endurance running. It is not the only fuel used during endurance running but it is the most easily accessible. Once you start to run out of glycogen reserves, your body turns to other fuels as a source of energy, such as fats. Fats are much harder to convert into useable forms of energy and so larger stores of glycogen will help to delay the onset of fatigue during endurance events.  Since Gunvar Ahlborg first discovered the benefits of carbohydrate loading in the 60’s there have been numerous studies that support his theory and indeed show that taking on high levels of carbohydrates within 3 days prior to an endurance event delays the onset of fatigue (there have also been significant studies that show the placebo effect plays a large role in this! But I won’t go into that now).

For 2 to 3 days prior to your race around 90% of your calories should come from carbohydrates (this is not true during periods of intense training as you also need lots of protein to repair damaged muscle tissue). Carbohydrate rich foods are easy to find and easy to incorporate large portions into your meals. Potatoes, sweet potato, wholegrain rice, wholegrain pasta etc are all great foods for carb loading and increasing those all-important glycogen stores.

However, my first piece of advice still stands; If you have never practiced this change of diet before then trying it for the first time in the lead up to a big race is definitely a bad idea. It’s a much better idea to try this a few times before a particularly tough training session, or before a long run, or even pick a few races that aren’t that important to you where you can practise diet changes. This way you’ll start to build a picture of what works for you and which foods your body responds well/badly too; by the time the big race comes around you’ll know exactly what to do and the whole ‘what to eat’ dilemma can be avoided.

For example, if your big race is London Marathon next year, then pick a local race in January/February time, perhaps a 10k or half marathon where you can practise carb loading in the days prior to this race. Try it a few more times before some of your long runs to make sure you’ve got it spot on.

If you have to travel to a race make sure you plan ahead. Take lots of carbohydrate rich snacks like cereal bars or sports bars. Low sugar sports drinks will do the trick too and there are some great powder mixes out there that you can mix into water for an added portion of easily digestible carbohydrate.

The night before

The night before your big race you should try to really fill up those glycogen stores without upsetting your stomach. The best foods for this are carbohydrate rich foods that are also low in fibre, such as white pasta, pancakes, potatoes (with skin removed, mashed potato is great), and bread. Fruit is also great for getting in carbohydrates but try to remove the skin before eating to get rid of any extra fibre that could upset your stomach. Try to avoid foods that are rich in fibre, protein or fats as these fill you up more and are harder for your body to digest.  You don’t want to still be digesting last night’s dinner during your race! Avoid things like red meat, fatty foods, beans and pulses at this stage.

Make sure you eat enough to be full but not overly full. Often people think they need to stuff as much as they can in to ensure they have plenty of energy the next day, if you do this you may not digest your food efficiently and you could risk having stomach problems during your race.

Conversely, it is also common to hear of people eating only a small portion the day before a race to avoid that ‘full’ feeling in the morning. This is also a bad idea, particularly for the longer endurance events (10k and up) as your body needs the energy to get through the race. A medium sized portion, enough to feel satisfied, is perfect.

Timing also plays an important role. Try to eat during the early evening to ensure there is plenty of time for your body to digest all your food properly before the race. Eating earlier in the evening also promotes better quality sleep, another important factor leading up to a race.

Race day

The morning of your race is a crucial time to get your fuel intake right. There is significant research that suggests eating a carbohydrate rich meal approximately 3 hours before an endurance event delays the onset of fatigue compared to not eating. Choose a breakfast that is high in carbohydrates but with a low glycaemic index (often referred to as ‘slow release’ carbohydrates). Eating sugary, high GI foods in the morning of your race will result in a spike in blood sugar levels and a subsequent fall before or during your race. Try to eat foods such as non-sugary cereals, porridge, brown bread, fruit (without skin) and carbohydrate powder mixes. This will keep your glycogen stores topped up without causing a sudden rise in blood sugar levels.

Try to eat around 2-3 hours before your race and keep the portion size small but satisfying. This will ensure that the food has enough time to digest but also make sure that you aren’t feeling hungry on the start line.

Again, it’s very important that you practice your pre-race meal routine during training or a less important race. This is something you can do before long runs so that your body gets used to the timings, quantity and type of food you eat before running. For example, If you do a long run every fortnight, try starting your run at the same time your big race starts, get up at the time you would on race day and have a good breakfast 2-3 hours before your run. Practice this at least 3 or 4 times before your race so you know what works for you.


In conclusion practice makes perfect. There are lots of studies out there that prove the benefits of various diets and show different foods to have positive effects on exercise. However, if your body isn’t used to it, don’t try it for the first time on the day of your big race. Practice our suggestions before some of your training runs and find out what works best for you. The better prepared you are the less room you leave for stressful situations and the more confident you can be going in to your race.

Thanks for reading and look for my next blog where I will discuss mid race nutrition for longer distance races.


About the author

Callum Jones is an engineering master’s graduate of the University of Bristol and middle distance runner who has spent long periods of time training in Kenya.  He began working for the Kenya Experience in October 2017.

“I’ve been an aspiring distance runner for the last 10 years and worked hard to improve my times year after year.  Training in Iten was an incredible experience for me, it really took my running and love for the sport to a new level and opened my eyes to a whole new mentality towards training. Working for Kenya Experience is fantastic as I can offer my knowledge of the sport and insight into the Kenyan running culture with our guests.”

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